Composite materials of an organic substance such as a resin and an inorganic material such as carbon are used in various fields. Examples of the composite materials include a carbon fiber reinforced plastic (CFRP) including a resin and carbon fibers, a glass fiber reinforced plastic (GFRP) including a resin and glass fibers, a mold coil including a resin and a metal member, and a motor coil including a varnish and a conductive coil.
In view of a recent increase in the disposal amount of used composite materials, development of a technique of reprocessing and reusing the same has been considered. For example, a method of collecting an inorganic material from a composite material by decomposing a resin in the composite material with a processing solution including a decomposition catalyst and an organic solvent, and separating the resin with the processing solution from the inorganic material, has been proposed as a method of reusing an inorganic material in a composite material including an epoxy resin or a polyester resin and an inorganic material (see, for example, Japanese Patent Application Laid-Open (JP-A) Nos. 2001-172426 and 2002-194137).